Attachment method using anodic bonding

Abstract

The invention relates to an anodic bonding method for bonding two elements with an intermediate layer. The invention especially, but not exclusively, relates to an anodic bonding method for between a metallic element and a heterogeneous element, for example a glass, artificial sapphire or ceramic element. The specificity and aim of the present invention is to produce an assembly that is gas-tight and fluid-tight, solderless, brazing- or welder-free and without organic compound (glue). The present method has multiple industrial applications, including making it possible to attach a watch-glass, typically made of mineral glass, sapphire or transparent or translucent ceramics, to a bezel or case middle of a watch case using the anodic bonding technique.

The invention claimed is: 
     
       1. An anodic bonding method between a first substrate and a second substrate comprising:
 interposing an intermediate layer between the first and second substrates; 
 assembly of the substrates at a determined bonding temperature; 
 application of an electric voltage between the first and the second substrate, 
 wherein said electric voltage comprises a pulsed or AC component with a frequency greater than 100 Hz, and in that said bonding temperature is less than 300° C. 
 
     
     
       2. The anodic bonding method of  claim 1 , wherein said electric voltage comprises a DC component. 
     
     
       3. The anodic bonding method of  claim 1 , wherein said bonding temperature is less than 200° C. 
     
     
       4. The anodic bonding method of  claim 1 , wherein said intermediate layer is a glass layer. 
     
     
       5. The anodic bonding method of  claim 4 , wherein the intermediate layer exhibits a chemical gradient and/or an oxidation gradient. 
     
     
       6. The anodic bonding method of  claim 1 , wherein said intermediate layer is a titanium oxide layer. 
     
     
       7. The anodic bonding method of  claim 6 , comprising a step of deposition of an oxidizable layer on one of the substrates, followed by an oxidation step. 
     
     
       8. The anodic bonding method of  claim 1 , comprising a step of functionalizing said intermediate layer with a reactive plasma. 
     
     
       9. The anodic bonding method of  claim 8 , wherein the reactive plasma includes oxygen. 
     
     
       10. The anodic bonding method of  claim 1 , wherein said first substrate is metallic, and said second substrate is a ceramic, or a glass, or a crystalline insulating material. 
     
     
       11. The anodic bonding method of  claim 10 , wherein the first substrate is made of steel, or stainless steel, or titanium, or gold, or aluminum, or platinum or an alloy thereof. 
     
     
       12. The anodic bonding method of  claim 10 , wherein the second substrate is a synthetic sapphire.